By calibration, we refer to the information needed to establish
the true amplitudes of signals.

There are two distinct aspects of calibration. First is signal
calibration, the process of establishing the relationship between the
sample values in analog-to-digital converter units (adus) and
the physical units of the signals (millivolts, millimeters of mercury,
etc.). Second is display calibration, the process of determining
standard scales for displaying various types of signals (e.g., 10
mm/mV, 1 mm/10 mmHg).